The proposed research will be composed of four parts: Part I. Characterization of rat liver myeloma RNA polymerase II by using analogs of ATP and UTP, i.e., 3' dATP and 3' dUTP. The purpose will be to determine if these 3'-deoxy analogs are competitive inhibitors of RNA polymerase II or if they are actually incorporated into RNA and thereby terminate RNA synthesis. Labeled and unlabeled nucleotides have been prepared in this laboratory. The results with (alpha-32p) 3' dATP show an incorporation into the 3'-end of mRNA. PART II. Elucidation of the RNA primer step in DNA replication by using 3'dUTP. This pyrimidine analog will overcome the problems that arise by using 3'dATP since ATP is required for RNA primer synthesis as well as the energy requiring step in DNA synthesis. With HeLa nuclei and alpha-polymerase, 3'dUTP is an excellent inhibitor of RNA and DNA synthesis. PART III. Comparison of ADP-ribosylation of nuclear proteins in nucleic from rat liver, Novikoff hepatoma, fetal rat liver, and xeroderma pigmentosum by using NAD analogs with modifications in the adenine and/or ribosyl moieties of NAD. The study will include the mechanism of covalent bond formation of ADPR and nuclear histones or nuclear proteins. PART IV: Biosynthesis of the nucleoside analogs, 3'-deoxyadenosine, 3-ethylidene-L-azetidine-2-carboxylic acid, the polyoxine, and minimycin. These studies have all been started and publications on the biosynthesis of these four nucleosides have appeared in the literature. BIBLIOGRAPHIC REFERENCES: Isono, K., and Suhadolnik, R. J., "The Biosynthesis of Natural and Unnatural Polyoxins by Streptomyces cacaoi", Arch. Biochem. Biophys. 173, 141 (1976). Lennon, M. B. and Suhadolnik, R. J., "Biosynthesis of 3'-Deoxyadenosine by Cordyceps militaris: Mechanism of Reduction", Biochim. Biophys. Acta, BBA #98568 (1976).